\documentclass{standalone}

\usepackage{tikz}
\usepackage{shapes}

\begin{document}
\begin{tikzpicture}

\fill[color=red](0.5,2.5)--++(1,0)--++(0,3)--++(-1,0)--cycle;

\grid{6}{9}{(-0.5,-0.5)}

\cross{teal}{(2,2)}
\cross{teal}{(3,4)}
\cross{teal}{(2,6)}

\end{tikzpicture}
\end{document}